Doctrine ORM : Joined table inheritance

Related to this previous topic : Database : Account table with Joined Tables Inheritance

I’ve created a joined tables inheritance in my database (MySQL) :

client_id attributes are both PK and FK.

Now I need to represent it with Doctrine ORM but I can’t find a solution of how to make that.

I created, with Symfony commands, the Client entity and for the ClientCompany entity I don’t know which relationship to use nor how to use the Client ID as primary key of the CompanyClient entity.

Does anyone know how to do it?

>Solution :

First of all, be really carefull with inheritance, this is a really good feature of doctrine but need to be used with a lot of cautious because of it’s counterpart.

For your case, i would advise to not try to put "person" and "company" under the same abstract "client" class for conception reason i already explain in this answer since a company and a person are totally different things: Symfony 6 inheritance Mapping : How to submit a form depends on a clicked radio button?

But i will still answer on how to properly do a join table inheritance :

AbstractClient.php

#[Entity]
#[InheritanceType('JOIN_TABLE')] 
#[DiscriminatorColumn(name: 'discr', type: 'string')]
#[DiscriminatorMap(['person' => Person::class, 'company' => Company::class])]
abstract class Client
{
    // you do not need clientType since it is hold by the "discr" column
    // And if you want to know what type your client is you can do it using   
    // if($client instanceof Person::class) { do something}
}

Person.php

#[Entity]
class Person extends Client
{
    // ...
}

Company.php

#[Entity]
class Company extends Client
{
    // ...
}

Take a look at #[InheritanceType('JOIN_TABLE')]
It will create one table for each entity and they will share ids.
If you create a company with id 2, there will be a client with id 2. So a Person with id 2 will never be possible.

But if you use 'SINGLE_TABLE' it will create only one table with all the field of all the entity which will be empty depending on which child you inserted inside.

But again i strongly advise you to not use join table inheritance for your usecase